Apparatus for the selective injection of fluids into geological formations



June 23, 1953 L. A. OGDEN ET AL APPARATUS FOR THE SELECTIVE INJECTION OF FLUIDS INTO GEOLOGICAL FORMATIONS 2 Sheets-Sheet 1 Filed Dec. 23, 1947 1| 1| w [.l Mu S Y h H RN EA b 0 ME U (/m E AM ND? Q h EGHC m VOCM T WL n mQ lull U u u .W m m 2 5 mm X0 ml 2 R v 3 2 Am mm on Q a an mu 5 mm mm June 23, 1953 A. OGDEN ET AL 2,643,208

Y mwmwus FOR THE SELECTIVE INJECTION F FLUIDS INTO GEOLOGICAL FORMATIONS 2 Sheets-Sheet 2 Filed Dec.. 23, 1947 a. a; i i I'll Z55 I 2:: I32; I 553 I P H63 INVENTORS.

BAURENC. (eom y mas c uesuav FIG.Z LAWRENCE L. MCDONALD (Md ll- Patented June 23, 1953 APPARATUS FOR THE SELECTIVE INJEC- TION OF FLUIDS INTO GEOLOGICAL FORMATION S Laurence A. Ogden, James R. MeChesney, and Lawrence L. McDonald, Tulsa, Okla., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio Application December 23, 1947, Serial No. 793,478

8 Claims.

This invention relates to repressuring and flooding of subterranean oil formations and is more concerned with method and apparatus for permitting selective injection of fluid into formations of low permeability.

In the flooding and repressuring of subterranean oil formations, it is common practice to seal off the formations of high permeability in order that the water, gas or other fiuid injected into the well bore will be forced into the formation of low permeability. In order to accomplish selective sealing, mechanical packers have been used as well as chemical sealing agents. In accordance with our invention, We use a collapsible or inflatable packer controlled by mechanism above the earths surface for sealing off the formations of high permeability and permitting the fluid to be injected into the formations of low permeability.

One of the objects of our invention is to p vide a method for selectively repressuring or flooding subterranean oil formations.

Another object of the invention is to provide apparatus for selectively sealing on" different formations along an earth bore.

Still another object of the invention is to provide a differential pressure-type expansible or collapsible packer for use in earth bores.

A further object of the invention is to provide apparatus for control at the earths surface of the dilferential pressure on a collapsible or expansible packer in an earth bore.

Still another object of the invention is to provide method and apparatus for controlling the volume and pressure of fluid injected into a well bore.

A still further object of the invention is to provide method and apparatus which will permit acidizing of selected strata along a well bore.

Other objects of the invention will become apparent from the following description and the accompanying drawing, of which Figure l is a diagrammatic View of the differential pressure control mechanism for controlling the pressure on the collapsible packer element shown in Figure 2;

Figure 2 is a vertical cross-sectional view of a well bore in which has been inserted a packer in accordance with our invention;

Figure 3 is a slightly different arrangement for injecting fluid into the earth bore and packer; and Figure 4 is still another modification of apparatus for injecting fluid into the formation and the packer.

Referring to the drawing, the numeral l indicates the inlet of a pipe line 3 to which water, hydrocarbon gas or other fluid is charged by means of a pump or compressor not shown. The pressure in line 3 is controlled by valve 5 which may be hand-operated or which may be automatically controlled to maintain a constant pressure on the downstream side thereof and provide against increase of pressure caused by plugging of the walls of the well bore. A pressure gauge 1 and a meter 8 are placed in the line on the downstream side of valve 5 in line 3, and a check valve 9 is also placed on the downstream side of valve 5 in the line 3 in order to prevent back-flow of fluid through the line in the event of failure of the pressure source at inlet l.

A pipe I lof smaller diameter than line 3 is connected to the latter on the upstream side of valve 5. A valve i3 is placed in line H in order to permit the line to be shut off. Differential pressure regulator i5 is placed in line II on the downstream side of valve it. The pressure regulator is adapted to open upwardly. The pressure regulator 55 comprises a closure element ll adapted to be seated on seat IS. The closure element I7 is connected to a stem 20. A diaphragm (not shown) located in the housing 2! is connected to a rod 23. A compression coil spring is held in place under desired compression between seat 27 on the upper end of stem 28, and the seat 28. Seat 28 is adapted to be adjusted upwardly or downwardly by means of the adjusting screw 29 mounted in a threaded opening in yoke 30. A line 3| connects line 3 on the downstream side of valve 5 to the space below the diaphragm in the housing 2|. A line 33 connects the line I l on the downstream side of the regulator l5 to the space above the diaphragm in the housing 2|. A check valve 35 is placed in line H between valve 113 and pressure regulator [5. The pressure gauge 3'! is placed in line H' on the downstream side of regulator I5.

A line 39 connects the line It on the downunder desired compression between seat 53 and seat 55 mounted on the end of stem 45. T e compression of the spring is adjusted by adj ing screw 56 mounted in threaded yoke A line 58 connects the space below or to the left of the diaphragm in housing :3! to the .line 39 at a point between the pressure regulator 4! and the line 3. A line 59 connects the space above or to the right of the diaphragm in housing 41 to line 39 to a point between the line II and the pressure regulator 4 I.

Line 3 is connected at a point beyond check valve 9 to tubing head EI (Figure 2) on well casing 63. Line H is connected at a point beyond pressure gauge 3'! to the upper end of well tubing 55.

Referring more particularly to Figure 2, there is illustrated a subterranean formation surrounding an earth bore showing two strata 81 of high permeability and low oil content spaced between three strata B9 of low permeability and high oil content. The well casing 63 is sunk to the top of highest formation as of low permeability and high oil content. Well tubing I55, which is of smaller diameter than the casing is disposed within the borehole. The tubing 65 has fastened to its outer wall at points opposite the subterranean formations of high permeability fluid impermeable expansible and/or collapsible envelopes II which may suitably be made of rubber, tightly woven and treated cloth or other expansible and/or collapsible material which is substantially impervious to gas and liquid. The lower end of the tubing 65 extends below the lowest packer and has perforations 85 below the lowest packer in order to permit fluid to pass therefrom into formation. The envelopes II are substantially of the same length as, or of slightly greater length than, the depth of the high perme ability formation which the envelope or sleeve is intended to seal. The ends of the envelope or sleeve II are fastened by rings or collars I3 to the outside of the tubing 65 in such manner as to prevent leakage of fluid therefrom and to prevent the envelopes from moving along the tubing. The thickness of the sleeve or envelope II should be such as not to require too much pressure to expand the envelope against the wall of the earth bore. We have found that a flexible, rubber envelope having a wall thickness of approximately {2 inch to one inch is satisfactory.

A circular disk I5 with an opening large enough to accommodate a small pipe IT is placed in the tubin 65 at a point above the topmost envelope or sleeve TI. The pipe IT, the closed upper end of which extends above the disk I5 and which is perforated adjacent its upper end as shown at I9, extends through the disk I5 to a point Within the lowermost sleeve or envelope 'II. The pipe I! is provided with outlets BI extending through tubing 65 into the space between the tubing 65 and each envelope II. The tubing 65 is provided with a series of perforations 83 between the disk I5 and the top of the uppermost envelope H and further series of perforations 85 at points opposite each formation of low permeability.

The operation of the apparatus is as follows: water, gas or other fluid which is to be used to flood or repressure the subterranean oil producing formations is forced through inlet I into pipe 3- at a pressure above that required to force the fluid into the producing formations of low permeability. Pressure of the fluid is reduced at valve 5 so that the pressure on the downstream side of the valve is sufficient to force the fluid into the producing formations. Accordingly a pressure differential is maintained in line 3 whereby the pressure in line 3 down stream of valve 5 is maintained at a pressure less than that applied through line II. The fluid enters the annular space between the well casing 63 and tubing 65, and is forced into the topmost formation 69 of low permeability.

With valve I3 open, pressure at the inlet of line 3 is exerted through line I I on the top of the diaphragm in housing 2I through line 33. Pressure in line 3 on the downstream side of valve 5 is exerted through line 3I on the lower side of the diaphragm in housing 2I. The compression of the coil spring 25 is such that this force plus the injection pressure on the underside of the diaphragm will hold the pressure regulator I5 in open position. The fluid pressure provided through line II is employed to maintain the expansible envelopes II in an inflated condition during the injection operations. At the outset of the injection procedure when the fluid pres-' sure is initially applied at inlet I the differential pressure regulator closure element I! in differential pressure regulator I5 will be held in an open position due to the force impressed upon the lower side of the diaphragm in housing 2| by spring 25 and the injection fluid pressure applied through line 3|. The force exerted by the spring is adjusted so that a pressure differential of from about 10 to 75 pounds per square inch above that occurring in line 3 obtains in line II. Therefore when the injection pressure desired is obtained in line 3 the pressure differential occurring in line II will be suflicient to maintain the packer element II in an inflated condition. When the packers II are inflated the pressure differential is impressed upon the upper side of the diaphragm in housing 2| via line 33. This force is of sufficient magnitude to overcome the force exerted on the underside of the diaphragm by spring 25 and the injection pressure provided through line 3|. Accordingly differential pressure regulator I5 will be closed by closure element Il engaging with seat I9. So long as the liminal injection pressure is ample for injection purposes differential pressure regulator I5 will remain closed. If the pressure in line II under these injection conditions decreases due to leaks in the packer inflation system or for other reasons this change will be reflected through line 33 and closure element Il will be unseated due to the unbalancing of the forces exerted upon the diaphragm contained in housing 2I. The regulator I5 will remain open until the desired predetermined pressure differential is again obatined. At this time the pressure regulator I5 will again close. Similarly the pressure regulator I5 will function for any demand increase or decrease in the injection pressure to maintain the desired predetermined pressure differential by operating in conjunction with pressure regulator 4| which operates as a by-pass relief type pressure differential regulator. This by-pass operation is hereinafter described.

As previously described, the fluid flows through line II into tubing 65, but cannot pass beyond the disk I5 since the disk blocks the passageway above and below it. The fluid in the tubing 65 is, therefore, caused to enter pipe 11 through perforations I9 and flow downwardly through pipe TI. The perforations I9 are placed a sufficient distance above the disk I5 to prevent any sediment that may collect on the disk from blocking the perforations. The fluid passing through pipe 11, which is at a pressure above the pressure of the fluid in the annular space between the casing 63 and tubing 65, leaves the pipe 11 through outlets 8| located inside the envelopes or sleeves H and, since the pressure is above the pressure of the fluid outside the envelopes, the envelopes are caused to expand and be held snugly against the surface of the well bore opposite the formations of high permeability. The pressure differential between the fluid on the outside and the inside of the envelope need only be sufficient to hold the envelope snugly against the well bore. We have found that this pressure may vary from approximately 10 to 75 pounds per square inch, and may be higher or lower depending on the ability of the envelope to stand higher pressures and the minimum pressure necessary to expand the envelope against the surface of the well bore.

The fluid in the well bore opposite the topmost formation 69 of low permeability is forced both into the formation and through orifices 83 into the tubing 65 below the disk 15, and passes downwardly in the annular space between the tubing 65 and pipe 11, being forced out of the tubing through perforations 85 into the several lower formations of low permeability.

In order to further protect the envelopes or sleeves against rupture caused by too large pressure differential between the inside and outside thereof, a second pressure regulator 4| is placed between the lines II and 3 as previously described. The pressure regulator 4| seats upwardly or seats when the rod 45 moves to the right. The pressure of the fluid on the downstream side of valve 5 is exerted on the underside of the diaphragm in housing 47 through line 58. Pressure in the line H, which is higher than the pressure exerted through line 53, is exerted on the upper or right side of the diaphragm in housing 4'! through line 59. The compression spring 5! is so adjusted that the force exerted by it plus the pressure in line 58 is greater than the pressure through line 59, thereby holding the regulator M in closed position. If for any reason the injection pressure, that is the pressure on the downstream side of valve 5, declines, as for example, due to failure of the pump or compressor feeding liquid or gas through inlet 1 or due to the fact that the fluid after a time enters the formations of low permeability more easily, the pressure exerted on the lower side of the diaphragm in housing 41 will decrease, while that pressure on the top of the diaphragm will remain constant because the fluid is trapped between the check valve in line i i and the envelopes H. As a result thereof, the regulator 4| will open permitting fluid to flow through the line 39 into the line 3, and thereby releasing excess pressure in the envelope H until the differential pressure between the inside and outside of H returns to the desired differential for which the regulator 4| is set. Thus, suflicient differential is maintained in the envelopes H to keep them inflated, but the differential is not permitted to rise above a predetermined amount which would cause rupture of the envelopes.

In order to permit the envelopes H to be deflated, as for example, when it is desired to withdraw the envelopes from the well bore, a line 8? controlled by valve 89 is connected to line II on the downstream side of regulator 15. By closing valve i3, thereby preventing further entrance of fluid into the tubing 65, and opening 6 valve 89, the pressure in the line H between the regulator 15 and the envelopes H is relieved with the result that the pressure on the outside of the envelopes H and the elasticity of the envelopes causes the envelopes to collapse. In order to assist in collapsing the envelopes ll, valve 5 may be opened to increase the pressure on the outside of the envelopes.

It will be apparent that other piping arrangements in the well may be resorted to in order to isolate the fluid pressure on the inside and the outside of envelopes ll. Some possible modified arrangements are shown in Figures 3 and 4.

Referring to Figure 3, instead of charging fluid to the sleeves or envelopes H through the pipe if, the fluid may be charged to the sleeves ll directly from the tubing 65. Tubing 65 is provided with perforations 39 inside the envelopes H in order to permit fluid to escape from the tubing 65 into the envelope. Pipe 11 will have an inlet 9| above the topmost sleeve H to permit fluid charged through the line 3 to pass downwardly through the annular space between the tubing and casing and then enter the pipe Ti and escape through outlets 93 into the formaations of low permeability.

If it is desired to inject fluid into the formation below the sleeve or envelope H while excluding it from the formation above it, the modification shown in Figure 4 may be used. In this modification, the tubing 65 is equipped with a perforated and bull-plugged nipple 95 below the packer "H which is fastened to the tubing by means of coupling 96. Sealing cups 9! are provided to prevent fluid from flowing from the annular space between tubing 65 and pipe 11 into nipple 95. Tubing 65 is perforated as shown at '89. Fluid for inflating the sleeve or envelope H is charged from pipe H through the tubing 65. Fluid for injection into the formation below the envelope H is charged through pipe 1! and enters the formation through the perforations 98 in the nipple 95. r

In the event it is desired to inject fluid into formations both above and below packer ll using the arrangement shown in Figure 4, additional fluid can be charged through line 3 into the annulus between the casing 53 and the tubing 65 In this case, line 3 would be divided and a separate pressure-reducing valve 5, meter 8; pressure gauge 1, and check valve 9 would be provided for the two branches connecting with the casing 63 and pipe T1. The lines 58 and 3| would also be manifolded and valved so that pressure from either or both lines could be im posed on the diaphragms in the pressure regulators l5 and 4|. This modification permits the volume and pressure of the fluid injected above and below the envelope to be individually controlled.

As previously pointed out, an automatic pressure regulator may be used instead of the handoperated valve 5. By substituting a pressurereducing regulator for the valve 5, the possibility of the envelopes ll deflating or collapsing due to the fact that the pressure required for injection of fluid into the producing formations increased to such an extent that it closely approaches the total pressure available at the inlet of line 3 is avoided. Such a situation may arise if the face of the well bore becomes partially plugged, decreasing its permeability.

The following is a description of an actual test made using apparatus in accordance with our invention. An 8 inch diameter hole was drilled 7 to a depth of 1461 feet and the hole continued to a depth of 1555 feet with a diameter of 6 inches. Casing having an O. D. of 5 inches was set and cemented to a depth of 145?: feet. The well was then plugged back to 1525 feet in order to shut off bottom hole water.

Gas injection was then commenced at a pressure of 18 pounds gauge at the rate of 25,000 cubic feet per day and continued for a period of almost one year, at the end of which time the pressure required to inject the gas at the same rate declined to 6 pounds per square inch.

In view of the fact that a conventional packer could not be run inside the casing having an I. D. of 4.892 inches, which would expand to the 6 inch diameter of the hole, it was decided to use an expansible differential type packer in accordance with this invention. A single packer was used having an over-all length of 23 feet with 1 foot on either end being reinforced for end connection. The packer was made of rubber having a Wall thickness {-2- inch. The outside diameter of the rubber packer was 4 inches, except at the ends which had an outside diameter of 3% inches in order to provide clearance to fit clamps to 2 inch 1. D. tubing. The packer was tested at the surface and was found to require a differential pressure of '75 pounds per square inch to fully inflate it against a 6.538 inch 1. D. pipe.

It was then run into the well on tubing and suspended to shut oi the formation at a depth between 1462 and 1483 feet. The packer was inflated by introducing gas under pressure of 75' pounds per square inch gauge and then the injection of gas into the formation was begun at the rate of 25,000 cubic feet per day at 18 pounds per square inch while maintaining a pressure of 90 pounds per square inch in the packer. The injection pressure required to inject the gas dropped by the next day to 11 pounds per square inch. At this pressure, the pressure in the packer was 81 pounds per square inch. The pressure gradually declined until at the end of approximately a weeks time, the pres sure required to inject the gas into the formation had declined to 8 pounds per square inch.

In order to deflate and raise the packer, the pressure on the inside of the packer was released by opening valve 89 and valve was opened to increase the injection pressure on the outside of the envelope to 18 pounds per square inch.

It will be seen that by means of the apparatus described and shown, a means is provided for quickly sealing off formations of high permeability in order to selectively flood or repressure oil producing formations of low permeability. By placing mechanical apparatus for controlling the pressure on the packing device at the surfac of the wall, any regulations required can be readily made, and in the event a defect arises in the apparatus, it is unnecessary to remove the entire packing device from the well.

What is claimed is:

1. An expansible and collapsible packer for earth bores comp-rising a pipe, a collapsible substantially fluid-impermeable envelope fastened to said pipe to define an enclosed space with the walls of said pipe, a first conduit connected to the pipe for supplying fluid to said envelope and a second conduit for supplying fluid to the earth bore around said enclosed space, and a means for maintaining a predetermined pressure differential in the said first conduit wherein the pressure in the first conduit is continuously maintained over and above that available in the sec- 0nd conduit, which comprises a means for sup plying fluid from a common pressure source through the first and second conduits to the inside and to the outside, respectively, of said packer, a pressure reducing valve in the second conduit applying fluid to the outside of said packer, a first pressure differential regulator disposed in the first conduit supplying fluid to the inside of said packer, said conduit supplying fluid to the outside of said packer being connected on the downstream side of said pressure reducing valve to said first differential pressure regulator to maintain said regulator in the open position, the conduit supplying fluid to the inside of said packer being connected to said first differential pressure regulator to maintain said regulator in a closed position, said regulator being adjusted to remain in open position until the pressure of the fluid charged to the inside of said packer exceeds the pressure of fluid charged to the outside of said packer by a predetermined amount and a second differential pressure regulator connected between said first and second conduits at points downstream of said first differential pressure regulator and said pressure reducing valve, said second regulator being activated by pressure of fluid on the inside and on the outside of said packer to remain in closed position until the pressure differential between the inside and outside of said packer exceeds a predetermined maximum.

2. Apparatus for maintaining a pressure differential between the inside and outside of an inflatable packer located in a well bore comprising means for supplying fluid from a common pressure source through first and second lines to the inside and to the outside respectively of said packer, a pressure reducing valve in the second line supplying fluid to the outside of said packer,

an automatic pressure regulator in the first line supplying fluid to the inside of said packer, said line supplying fluid to the outside of said packer being connected on the downstream side of said pressure-reducing valve to said pressure regulator to maintain said regulator in open position, the line supplying fluid to the inside of said packer being connected to said pressure regulator to maintain said regulator in a closed position, said regulator being adjusted to remain in open position until the pressure of fluid charged to the inside of said packer exceeds the pressure of fluid charged to the outside of said packer by a predetermined amount.

3. Apparatus in accordance with claim 2 including a check valve in said line for charging fluid to the inside of said packer, said valve being located between the common pressure source and said pressure regulator.

4. Apparatus in accordance with claim 3 including a check valve in the line for charging fluid to the outside of said packer, said check valve being located on the downstream side of the pressure reducing valve.

5. Apparatus in accordance with claim 4 including a second automatic pressure regulator, connected between said lines feeding fluid to the inside and outside of said packer at points on the downstream side of said first mentioned pressure regulator and said pressure reducing valve, said second regulator being activated by pressure of fluid on the inside and on the outside of said packer to remain in closed position until the pressure differential between the inside and outside of said packer exceeds a predetermined maximum.

6. Apparatus in accordance with claim including means for releasing pressure in the line supplying fluid to the inside of the packer.

7 An expansible and collapsible packer for earth bores in accordance with claim 1 in which the pipe and the collapsible, substantially fluidimpermeable envelope fastened to said pipe to define an enclosed space with the walls of said pipe comprises a pipe adapted to extend into the earth bore, a collapsible and substantially fluidimpermeable envelope secured to the outside wall of said pipe to define a closed space with the walls of said pipe, said pipe being perforated above and below said envelope and being fitted with an annular, transverse partition superposed above said topmost perforations, a second pipe longitudinally mounted inside said first mentioned pipe and of smaller diameter than said first mentioned pipe, said second mentioned pipe extending through said transverse partition, terminating at a point above said partition and having an opening adjacent the upper end thereof and an outlet therefrom into the space between said envelope and said first mentioned pipe, said transverse partition providing a fluid-tight barrier in the annular space provided by said first and second mentioned pipes.

8. An expansible and collapsible packer for earth bores in accordance with claim 1 in which the pipe and the collapsible, substantially fluidimpermeable envelope fastened to said pipe to define an enclosed space with the walls of said pipe comprises a pipe adapted to extend into the earth bore, a collapsible, substantially fluid-impermeable envelope secured to the outside wall of said pipe to define a closed space with the walls 10 of said pipe, said pipe being perforated within the space enclosed by said envelope to permit the passage of fluid from said pipe into the closed space defined by said envelope, a second pipe mounted longitudinally within said first mentioned pipe and of smaller diameter than that of said first mentioned pipe, the inlet and outlet of said second pipe extending through the walls of said first mentioned pipe topermit th passage of fluid through said second mentioned pipe independently of said first mentioned pipe.

LAURENCE A. OGDEN. JAMES R. McCI-IESNEY. LAWRENCE L. McDONALD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 31,567 Spooner Feb. 26, 1861 1,000,583 Cooper Aug. 15, 1911 1,604,644 Heyser Oct, 26, 1926 1,861,332 Waltz May 31, 1932 2,107,006 Lang Feb. 1, 1938 2,133,730 Brundred Oct. 18, 1938 2,210,546 Hassler Aug. 6, 1940 2,301,624 Holt Nov. 10, 1942 2,316,383 Abercrombie Apr. 13, 1943 2,347,769 Crites May 2, 1944 2,357,189 Erwin Aug. 29, 1944 2,372,631 Stevenson et al. Mar. 27, 1945 FOREIGN PATENTS Number Country Date 38,065 Netherlands May 15, 1936 

1. AN EXPANSIBLE AND COLLAPSIBLE PACKER FOR EARTH BORES COMPRISING A PIPE, A COLLAPSIBLE SUBSTANTIALLY FLUID-IMPERMEABLE ENVELOPE FASTENED TO SAID PIPE TO DEFINE AN ENCLOSED SPACE WITH THE WALLS OF SAID PIPE, A FIRST CONDUIT CONNECTED TO THE PIPE FOR SUPPLYING FLUID TO SAID ENVELOPE AND A SECOND CONDUIT FOR SUPPLYING FLUID TO THE EARTH BORE AROUND SAID ENCLOSED SPACE, AND A MEANS FOR MAINTAINING A PREDETERMINED PRESSURE DIFFERENTIAL IN THE SAID FIRST CONDUIT WHEREIN THE PRESSURE IN THE FIRST CONDUIT IS CONTINUOUSLY MAINTAINED OVER AND ABOVE THAT AVAILABLE IN THE SECOND CONDUIT, WHICH COMPRISES A MEANS FOR SUPPLYING FLUID FROM A COMMON PRESSURE SOURCE THROUGH THE FIRST AND SECOND CONDUITS TO THE INSIDE AND TO THE OUTSIDE, RESPECTIVELY, OF SAID PACKER, A PRESSURE REDUCING VALVE IN THE SECOND CONDUIT APPLYING FLUID TO THE OUTSIDE OF SAID PACKER, A FIRST PRESSURE DIFFERENTIAL REGULATOR DISPOSED IN THE FIRST CONDUIT SUPPLYING FLUID TO THE INSIDE OF SAID PACKER, SAID CONDUIT SUPPLYING FLUID TO THE OUTSIDE OF SAID PACKER BEING CONNECTED ON THE DOWNSTREAM SIDE OF SAID PRESSURE REDUCING VALVE TO SAID FIRST DIFFERENTIAL PRESSURE REGULATOR TO MAINTAIN SAID REGULATOR IN THE OPEN POSITION, THE CONDUIT SUPPLYING FLUID TO THE INSIDE OF SAID PACKER BEING CONNECTED TO SAID FIRST DIFFERENTIAL PRESSURE REGULATOR TO MAINTAIN SAID REGULATOR IN A CLOSED POSITION, SAID REGULATOR BEING ADJUSTED TO 